Chickenpox vaccine: What you need to know. Centers for Disease Control and Prevention website. Available at:
http://www.cdc.gov/vaccines/hcp/vis/vis-statements/varicella.html. Updated June 18, 2013. Accessed November 12, 2015.

Immunization schedules. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/vaccines/schedules/index.html. Updated January 26, 2015. Accessed November 12, 2015.